Compression tool for electrical connectors

ABSTRACT

THE INVENTION RELATES TO A COMPRESSION TOOL FOR CRIMPING CONNECTOR LUGS ABOUT ELECTRICAL CONDUCTORS, THE TOOL HAVING A SLIDING TRAY TO ACCEPT CONNECTOR BLOCKS WITH A PLURALITY OF LUGS PRE-INSTALLED THEREIN AND, BY USING THE CONNECTOR BLOCK AS ONE-HALF OF THE CRIMPING DIE MEANS, TO SELECTIVELY AND SEQUENTIALLY CRIMP THE LUGS ABOUT A LIKE NUMBER A ELECTRICAL CONDUCTORS.

Oct. 12, 1971 D. EPPLER 3,611,782

COMPRESSION TOOL FOR ELECTRICAL CONNECTORS Filed April 8, 1969 3 Sheets-Sheet 1 lNl/la'N'I'OR. MAI/EL EPPL ER 3 Sheets-Sheet P,

D. EPPLER INVIrIN'I'U/f. DAN/EL EPPLER )VQV 41 ronwz r5 Illa-ll w ll]! COMPRESSION TOOL FOR ELECTRICAL CONNECTORS Filed April 8. 1969 Oct. 12, 1971 FIG.

Oct. 12, 1971 o. EPPLER COMPRESSION TOOL FOR ELECTRICAL CONNECTORS Filed April 8, 1969 3 Sheets-Sheet 5 IN VI'IN'I'UR. DAN/EL E'PPL ER Ji/F" f 24279.]

A TTORA/[XS United States Patent.

3,611,782 COMPRESSION TOOL FOR ELECTRICAL CONNECTORS Daniel Eppler, Toms River, N.J., assignor to Thomas & Betts Corporation, Elizabeth, N .1. Filed Apr. 8, 1969, Ser. No. 814,348 Int. Cl. B21d 9/08 US. Cl. 72410 3 Claims ABSTRACT OF THE DISCLOSURE The invention relates to a compression tool for crimping connector lugs about electrical conductors, the tool having a sliding tray to accept connector blocks with a plurality of lugs pre-installed therein and, by using the connector block as one-half of the crimping die means, to selectively and sequentially crimp the lugs about a like number of electrical conductors.

This invention relates to improvements in compression tools for applying electrical connector lugs to electrical conductors toeffect a mechanical and electrical bond between the lugs and the conductors. More particularly, this invention relates to a fixture for a compression tool which will provide automatic and sequential application of lugs, which have been premounted in connector blocks, to corresponding electrical conductors.

In assembling connector blocks for electrical or electronic equipment, it has been the common practice for the manufacturer to follow a two-stage procedure. First, a separate connector lug is applied to each electrical conductor which is to terminate at the connector block. The usual method of application is to use a hand operated plier-type compression tool to compress or crimp the ears of the lug about the conductor wire. This forms a socalled solderless connection and provides a good mechanical and electrical bond between the wire and the lug in less time and with less skill than it takes to make a proper soldered joint.

Secondly, the lug with wire attached is inserted into a connector block. Connector blocks are normally made of some relatively hard and strong non-conductive plastic material, such as Bakelite. They are molded into a series of transverse compartments, each of which will receive one lug. The compartments are separated by partitions of the sameplastic, formed in the molding operation, so as to prevent electrical contact between adjacent lugs or the conductor wires attached thereto.

The above described assembly procedure has several disadvantages. Since the crimping and inserting steps are performed separately, the assembly takes more time than if it could be accomplished in only one step. Furthermore, when the operator touches the lugs in the act of inserting them into the connector block, he may leave fingerprints which cause an oxide film to form and increase the surface resistance of the lug. This is especially detrimental to spring type lugs designed to make sliding electrical contact with mating lugs on a similar connector block when both are inserted in a connector block housing.

In addition to possibly spoiling the surface finish of the lug, manual insertion into a connector block compartment may also cause twisting or misalignment of the lug, resulting in improper electrical contact between mating lugs.

This invention remedies the above disadvantages. Briefly, it consists of four main parts: a compression tool having opposed jaws, a slotted base mounted on one of the jaws, a sliding tray mounted in the slot of the base in reciprocal sliding relationship to the base, and a double ratchet lock for controlling the motion of the tray with respect to the base.

Patented Oct. 12, 1971 p ICC In operation, the base of the sliding tray fixture is mounted on a compression tool which is adapted to compress the ears of a connector lug around an electrical conductor. Such a tool may be manually operated or power operated-either semiautomatic or fully automatic. A connector block which has been factory preassembled with connector lugs, is clamped in the sliding tray. A sawtooth ratchet on the tray cooperates with double ratchet pawls mounted on the base so as to permit positioning of the lug in the first compartment of the connector block directly underneath the crimping die of the compression tool. The end of a wire, from which the insulation has been stripped, is then placed between the ears of the lug. The compression tool is next operated to cause the crimping die to close over the lug and compress it around the wire.

Upon release of the die, the ratchet pawls are actuated to permit the tray to slide or index so that the lug in the second compartment is positioned directly under the crimping die. This process is repeated until all the lugs in the connector block have been compressed about their respective conductors.

Accordingly, it is an object of this invention to permit attachment of wires to factory preassembled connector blocks without the need for the operator to touch the lugs.

It is another object of the invention to provide a fixture for a lug compression tool which will automatically and sequentially position lugs, which are preassembled in a connector block, under the crimping die.

It is another object of the invention to provide a sliding tray fixture which is adaptable to both manually-operated and power-operated compression tools.

It is another object of. the invention to permit attachment of wires to lugs in a factory preassembled connector block in one operation rather than the two steps heretofore required.

These and other objects and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a perspective view of the sliding tray fixture of the invention as mounted in a hand operated plier type of compression tool;

FIG. 2 illustrates a partially broken perspective view of the top of the fixture with a preassembled connector block in place;

FIG. 3 illustrates a partially broken rear elevation view of the fixture with the crimping jaws of the compression tool fully open;

'FIG. 4 illustrates a partially broken rear elevation view of the fixture with the crimping die of the compression tool just closing on a lug;

FIG. 5 illustrates a partially broken rear elevation view of the fixture with the crimping die of the compression tool fully closed on a lug;

FIG. 6 illustrates a plan view of the fixture mounted in the compression tool;

FIG. 7 illustrates a cut-away view taken on line 7-7 of FIG. 6;

FIG. 8 illustrates a partially broken side elevation view of the hinge mechanism of the plier-type compression tool with jaws open; and

FIG. 9 illustrates a partially broken side elevation view of the hinge mechanism of the compression tool with jaws partially closed.

Referring to FIGS. 1, 3, 6 and 7, the sliding tray fixture has a slotted base 1 and a sliding tray 2. Extending longitudinally along the bottom of the tray 2 is a dovetail 3 which fits into the mating slot 4 in the base 1. The tray 2 can thus slide longitudinally in the base 1 but is constrained from any other motion with respect to the base. Along the rear of the tray 2 is a downward facing ratchet 5. The teeth of ratchet 5 are alternatively engaged by holding pawl 6 or locking pawl 7, both of which are pivotally secured by shoulder screw 8 to bracket 9 depending from slotted base 1. Coil spring 10 creates a tension on the tang of locking pawl 7 tending to rotate the wedge of pawl 7 into locking engagement with ratchet 5.

The base 1 has an integral mounting stud 11 which permits the sliding tray fixture to be mounted in the reciprocating jaw 12 of the plier-type compression tool 13 by means of locking pin 14. Compression tool 13 has a fixed L-head 15 in which is mounted crimping die 16.

Referring to FIGS. 6 and 7, base 1 has at one end a spring housing 17 which accommodates a special prerolled fiat spring 18, preferably of a type known as a negator spring. Such a spring has the tendency, when unrolled, to roll itself back up with a constant tension independent of the length which has been unrolled.

Spring 18 is coiled around bushing 19 which is rotatably secured Within spring housing 17 by screw 20 and housing cover 23. The outer end of spring 18 is led through spring channel 21 in slotted base 1 and secured to the bottom of sliding tray 2 by rivet 22. Spring 18 thus exerts a constant tension force on sliding tray 2 urging it toward the spring housing end of base 1. Motion of tray 2 is prevented by holding pawl 6 when compression tool 13 is in its fully open position or by locking pawl 7 when tool 13 is in a partially closed or fully closed position. The functions of holding pawl 6 and locking pawl 7 will be more completely explained below.

Referring to FIG. 2, sliding tray 2 is adapted to receive a factory preassembled connector block 24. Such a preassembled connector block is more fully described in my copending patent application No. 814,349 filed Apr. 8, 1969 and entitled, Wiring Connector Block. Generally, the connector block 24 is molded of hard, high tensile strength plastic, such as ABS plastic or glass filled plastic. Separate open transverse compartments 25 are provided for each connector lug 31. Lugs 31 are factory preassembled in connector block 24 and are held in place by side yoke 26 and center yoke 27. The portion of each compartment between side yoke 26 and center yoke 27 is designated as the crimping cavity 28. The bottom of each crimping cavity 28 has a molded hardened anvil 29 in the shape of an oval convex button. At each end of the connector block 24 are shoulders 30 which serve to subsequently properly assemble blocks 24 into connector housings (not shown).

Lugs 31 are made of a strip of malleable, conductive metal, such as copper, and are fashioned with crimping ears 32-at one end and tongue 33 at the other. Crimping cars 32 are adapted to wrap tightly around conductor wire 34 upon the closing of reciprocating jaw 12, carrying the sliding tray fixture with connector block 24, against crimping die 16.

Referring to FIGS. 1, 8 and 9, the frame of compression tool 13 is extended at its lower end into fixed handle 34. Movable handle 35 is pivotally mounted to the frame by means of hinge link 36 and pins 37 and 38. Hinge link 36 permits relative rotary motion between movable handle 35 and fixed handle 34 to be converted into relative reciprocal motion between reciprocating jaw 12 and the frame of compression tool 13 through pin 39, which connects the tang of movable handle 35 to the bottom of reciprocating jaw 12.

Movable handle 35 is normally held in the open position by cantilever spring 40, as shown in FIG. 8. As movable handle 35 is brought toward fixed handle 34 by squeezing the handles together, link 36 rotates counterclockwise about pin 37. At the same time, handle 35 rotates clockwise about pin 38 and the angle formed by link 36 and the tang of handle 35 tends to increase. The result is to move reciprocating jaw 12 upward in relation to the frame of tool 13. As handle 35 continues to be moved toward handle 34, the teeth of ratchet 42 engage pawl 41 which is rotatably mounted on pin 37. This engagement causes pawl 41 to rotate slightly clockwise against the restraining force of spring 43. So long as handles 34 and 35 are being squeezed together, pawl 41 will click past each tooth of ratchet 42 in turn. If the operator releases his grip after pawl 41 has passed the first, second or third teeth, pawl 41 will wedge against the back side of the respective tooth so that cantilever spring 40 cannot force the handles apart, as shown in FIG. 9. This feature permits the operator to partially close handles 34 and 35 and then to temporarily release his grip while making a final inspection of the relative position of lug 31 and Wire 34' under crimping die 16 without causing the handles to spread apart and allow sliding tray 2 to index to its next position. After he is satisfied that the terminal is ready for crimping, the operator squeezes handles 34 and 35 fully together. This brings pawl 41 past the fourth and last tooth of ratchet 42. The pull of spring 43 then swings pawl 41 back counter-clockwise. When the operator releases his grip, the engagement of the back sides of the teeth of ratchet 42 as the handles open will rotate pawl 41 still further counterclockwise, and it will click past each tooth without Wedging.

Having described most of the operating parts of a preferred form of the invention, as well as the parts of the compression tool component chosen by way of illustration and example, I shall now describe a complete cycle of operation whereby the objects and advantages of my invention shall become clear.

The first step is to load connector block 24, preassembled with lugs 31, onto sliding tray 2. In order to do this, tray 2 must slide away from spring housing 17 until carriage stop 44 (FIG. 6) bears against the side frame of compression tool 13.

Referring to FIGS. 3, 4 and 5, which show the jaws of compression tool 13 fully open, partially closed, and fully closed, respectively, tray 2 can he slid past ratchet pawls 6 and 7 in all positions of the jaws except the fully open position. In this position (FIG. 3), holding pawl 6 will not permit tray 2 to slide past either tooth 5a or tooth 5b because of the locking action of stop 45 which is mounted on the frame of compression tool 13. When the jaws of compression tool 13 have been partially closed (FIG. 4), reciprocating jaw 12 is raised relative to stop 45, thus dropping holding pawl 6 from engaging relationship with ratchet 5. Although locking pawl 7 will prevent motion of sliding tray toward spring housing 17, it will permit the teeth of ratchet 5 to click past it in the opposite direction by rotating clockwise on shoulder screw 8 against the restraining force of spring 10. When carriage stop 44 fetches up against the frame of compression tool 13, handles 34 and 35 are released, the jaws open fully under the action of cantilever spring 40, and stop 45 rotates holding pawl 6 into engagement with ratchet tooth 5a.

Once sliding tray 2 is in its starting position, connector block 24 is loaded onto the tray by rotatably retracting spring-loaded thumb latch 48, slipping retaining shoulder 30 at one end of connector block 24 into slotted stop 47, laying connector block 24 into the tray, and releasing thumb latch 48.

The tool is now loaded and ready to crimp the first lug. In order to key the description of the crimping cycle to the illustrations of FIGS. 3, 4 and 5, however, I will assume that the first lug has already been crimped and the tool is ready to crimp the second lug as shown.

The appropriate wire 34', from the end of which the insulation has been stripped, is inserted between the ears of the lug to be crimped. Movable handle 35 is then rotated toward fixed handle 34, thus closing the jaws of compression tool 13. As jaw 12 rises in relation to stop 45, holding pawl 6 is caused to rotate out of engagement with ratchet tooth 5a by the pressure exerted by shoulder 49 of locking pawl 7 against face 50 of holding pawl 6. At the same time, the wedge of locking pawl 7 rises to engage aermsz the face of tooth e as the tension of spring 18 pulls sliding tray 2 towards spring housing 17 (FIG. 4).

The pitch of the teeth of ratchet 5 and their location relative to locking pawl 7 and slotted stop 47 is such that when locking pawl 7 engages each tooth face in turn, crimping die 16 is centered directly over each succeeding crimping cavity 28 in connector block 24. Consequently, as the operator continues to squeeze handles 34 and 35, reciprocating jaw 12 rises until ears 32 of lug 31 engage crimping die 16 and, by the opposing force between anvil 29 and die 16, the ears are tightly crimped about wire 34.

As handles 34 and 35 are released, holding pawl 6 is rotated clockwise by stop 45 until face 50 bears against shoulder 49 of locking pawl 7. Continued clockwise rotation of holding pawl 6 as crimping tool 13 is released to the fully open position causes clockwise rotation of locking pawl 7 out of engagement with the face of ratchet tooth 5e. The tension of spring 18 then operates to pull sliding tray 2 towards spring housing 17 until ratchet tooth 5c bears against holding pawl 6. The tool is then ready for the next crimping cycle, which is repeated until all lugs 31 have been crimped about their respective wires 34.

It can thus be seen that the invention provides a sliding tray fixture for a compression tool; the combination device not only is simpler to use for the formation of solderless electrical connections than the compression tool by itself, but also is capable of forming all connections for a complete connector block either semi-automatically or fully automatically. The combination tool, by providing a secure mounting for the connector block which has been preassembled with connector lugs, eliminates the need either to try to hold both wire and lug in proper juxtaposed relation with the fingers of one hand while squeezing the handles of a compression tool with the other, or to take the extra step of securing the lug in a bench-mounted vise or clamp.

The invention still further reduces labor cost by producing a completely wired and assembled connector block in less time than it formerly took to crimp the separate lugs on their respective wires. The invention eliminates the labor and scrap loss which formerly occurred when a lug, after being crimped to a conductor, was damaged during insertion in the connector block and had to be replaced. The invention eliminates subsequent equipment failures resulting from lugs which are bent or misaligned during insertion in the connector blocks or which become corroded due to handling during the crimping and insertion operation.

Having thus described the invention, it is not intended that it be so limited; as changes may be made therein without departing from the scope of the invention. Accordingly it is intended that the subject matter described above and shown in the drawings be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A compression tool for sequentially crimping a plurality of electrical connecting devices disposed in an elongated insulating electrical connecting block comprising:

first and second cooperating crimping jaws, the first jaw being fixed and carrying a crimping die, the sec- 0nd jaw being reciprocally movable towards and away from said first jaw along a predetermined path;

an elongated slotted base secured to said second jaw and extending perpendicularly to said predetermined path;

a spring-loaded, connector block supporting tray slidably mounted in said slotted base and including a sawtooth rack disposed along the longitudinal axis of said tray; and

a double pawl stepping arrangement including a holding pawl and a separate locking pawl which are concentrically and rotatably mounted on said slotted base, said locking pawl being urged by a spring into locking engagement with said sawtooth rack, with said holding pawl and locking pawl coacting in such manner whereby the holding pawl rotatably disengages the locking pawl as the jaws are opened and simultaneously holds the sliding tray in position for the next step in the crimping sequence.

2. A compression tool as in claim 1 wherein the first jaw is formed integral with a first elongated handle, and the second movable jaw is operatively associated with a second elongated handle pivotally connected to said first handle.

3. A compression tool as in claim 2 wherein a lug is fixedly mounted on said first elongated handle, which lug coacts with said holding pawl to rotatably disengage the locking pawl as the jaws are opened.

References Cited UNITED STATES PATENTS 3,420,086 7/1969 Long et all 29203 689,721 12/1901 Holland 724l0 2,678,443 5/1954 Lindstrom 29243.56 2,892,368 6/1959 Demler 7'2404 3,075,198 l/l963 Over 724l0 3,230,758 l/l966 Klinger 72-4l0 CHARLES W. LANHAM, Primary Examiner MICHAEL J. KEENAN, Assistant Examiner US. Cl. X.R. 29-203 H, 243.56 

